[bpf-next,2/5] bpftool: Fix missing BTF output for json during map dump
diff mbox series

Message ID 20200114224406.3027562-1-kafai@fb.com
State Changes Requested
Delegated to: BPF Maintainers
Headers show
Series
  • bpftool: Support dumping a map with btf_vmlinux_value_type_id
Related show

Commit Message

Martin KaFai Lau Jan. 14, 2020, 10:44 p.m. UTC
The btf availability check is only done for plain text output.
It causes the whole BTF output went missing when json_output
is used.

This patch simplifies the logic a little by avoiding passing "int btf" to
map_dump().

For plain text output, the btf_wtr is only created when the map has
BTF (i.e. info->btf_id != 0).  The nullness of "json_writer_t *wtr"
in map_dump() alone can decide if dumping BTF output is needed.
As long as wtr is not NULL, map_dump() will print out the BTF-described
data whenever a map has BTF available (i.e. info->btf_id != 0)
regardless of json or plain-text output.

In do_dump(), the "int btf" is also renamed to "int do_plain_btf".

Fixes: 99f9863a0c45 ("bpftool: Match maps by name")
Cc: Paul Chaignon <paul.chaignon@orange.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/bpf/bpftool/map.c | 42 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

Comments

Andrii Nakryiko Jan. 15, 2020, 1:34 a.m. UTC | #1
On Tue, Jan 14, 2020 at 2:45 PM Martin KaFai Lau <kafai@fb.com> wrote:
>
> The btf availability check is only done for plain text output.
> It causes the whole BTF output went missing when json_output
> is used.
>
> This patch simplifies the logic a little by avoiding passing "int btf" to
> map_dump().
>
> For plain text output, the btf_wtr is only created when the map has
> BTF (i.e. info->btf_id != 0).  The nullness of "json_writer_t *wtr"
> in map_dump() alone can decide if dumping BTF output is needed.
> As long as wtr is not NULL, map_dump() will print out the BTF-described
> data whenever a map has BTF available (i.e. info->btf_id != 0)
> regardless of json or plain-text output.
>
> In do_dump(), the "int btf" is also renamed to "int do_plain_btf".
>
> Fixes: 99f9863a0c45 ("bpftool: Match maps by name")
> Cc: Paul Chaignon <paul.chaignon@orange.com>
> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> ---

just one nit below

Acked-by: Andrii Nakryiko <andriin@fb.com>

>  tools/bpf/bpftool/map.c | 42 ++++++++++++++++++++---------------------
>  1 file changed, 20 insertions(+), 22 deletions(-)
>
> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> index e00e9e19d6b7..45c1eda6512c 100644
> --- a/tools/bpf/bpftool/map.c
> +++ b/tools/bpf/bpftool/map.c
> @@ -933,7 +933,7 @@ static int maps_have_btf(int *fds, int nb_fds)
>
>  static int
>  map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
> -        bool enable_btf, bool show_header)
> +        bool show_header)
>  {
>         void *key, *value, *prev_key;
>         unsigned int num_elems = 0;
> @@ -950,18 +950,16 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
>
>         prev_key = NULL;
>
> -       if (enable_btf) {
> -               err = btf__get_from_id(info->btf_id, &btf);
> -               if (err || !btf) {
> -                       /* enable_btf is true only if we've already checked
> -                        * that all maps have BTF information.
> -                        */
> -                       p_err("failed to get btf");
> -                       goto exit_free;
> +       if (wtr) {
> +               if (info->btf_id) {

combine into if (wtr && info->btf_id) and reduce nestedness?


> +                       err = btf__get_from_id(info->btf_id, &btf);
> +                       if (err || !btf) {
> +                               err = err ? : -ESRCH;
> +                               p_err("failed to get btf");
> +                               goto exit_free;
> +                       }

[...]
Martin KaFai Lau Jan. 15, 2020, 5:54 a.m. UTC | #2
On Tue, Jan 14, 2020 at 05:34:33PM -0800, Andrii Nakryiko wrote:
> On Tue, Jan 14, 2020 at 2:45 PM Martin KaFai Lau <kafai@fb.com> wrote:
> >
> > The btf availability check is only done for plain text output.
> > It causes the whole BTF output went missing when json_output
> > is used.
> >
> > This patch simplifies the logic a little by avoiding passing "int btf" to
> > map_dump().
> >
> > For plain text output, the btf_wtr is only created when the map has
> > BTF (i.e. info->btf_id != 0).  The nullness of "json_writer_t *wtr"
> > in map_dump() alone can decide if dumping BTF output is needed.
> > As long as wtr is not NULL, map_dump() will print out the BTF-described
> > data whenever a map has BTF available (i.e. info->btf_id != 0)
> > regardless of json or plain-text output.
> >
> > In do_dump(), the "int btf" is also renamed to "int do_plain_btf".
> >
> > Fixes: 99f9863a0c45 ("bpftool: Match maps by name")
> > Cc: Paul Chaignon <paul.chaignon@orange.com>
> > Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> > ---
> 
> just one nit below
> 
> Acked-by: Andrii Nakryiko <andriin@fb.com>
> 
> >  tools/bpf/bpftool/map.c | 42 ++++++++++++++++++++---------------------
> >  1 file changed, 20 insertions(+), 22 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> > index e00e9e19d6b7..45c1eda6512c 100644
> > --- a/tools/bpf/bpftool/map.c
> > +++ b/tools/bpf/bpftool/map.c
> > @@ -933,7 +933,7 @@ static int maps_have_btf(int *fds, int nb_fds)
> >
> >  static int
> >  map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
> > -        bool enable_btf, bool show_header)
> > +        bool show_header)
> >  {
> >         void *key, *value, *prev_key;
> >         unsigned int num_elems = 0;
> > @@ -950,18 +950,16 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
> >
> >         prev_key = NULL;
> >
> > -       if (enable_btf) {
> > -               err = btf__get_from_id(info->btf_id, &btf);
> > -               if (err || !btf) {
> > -                       /* enable_btf is true only if we've already checked
> > -                        * that all maps have BTF information.
> > -                        */
> > -                       p_err("failed to get btf");
> > -                       goto exit_free;
> > +       if (wtr) {
> > +               if (info->btf_id) {
> 
> combine into if (wtr && info->btf_id) and reduce nestedness?
There is other logic under the same "if (wtr)".
Thus, it is better to leave it as is.
and this indentation will be gone in patch 5.

> 
> 
> > +                       err = btf__get_from_id(info->btf_id, &btf);
> > +                       if (err || !btf) {
> > +                               err = err ? : -ESRCH;
> > +                               p_err("failed to get btf");
> > +                               goto exit_free;
> > +                       }
> 
> [...]
Andrii Nakryiko Jan. 15, 2020, 6:36 a.m. UTC | #3
On Tue, Jan 14, 2020 at 9:54 PM Martin Lau <kafai@fb.com> wrote:
>
> On Tue, Jan 14, 2020 at 05:34:33PM -0800, Andrii Nakryiko wrote:
> > On Tue, Jan 14, 2020 at 2:45 PM Martin KaFai Lau <kafai@fb.com> wrote:
> > >
> > > The btf availability check is only done for plain text output.
> > > It causes the whole BTF output went missing when json_output
> > > is used.
> > >
> > > This patch simplifies the logic a little by avoiding passing "int btf" to
> > > map_dump().
> > >
> > > For plain text output, the btf_wtr is only created when the map has
> > > BTF (i.e. info->btf_id != 0).  The nullness of "json_writer_t *wtr"
> > > in map_dump() alone can decide if dumping BTF output is needed.
> > > As long as wtr is not NULL, map_dump() will print out the BTF-described
> > > data whenever a map has BTF available (i.e. info->btf_id != 0)
> > > regardless of json or plain-text output.
> > >
> > > In do_dump(), the "int btf" is also renamed to "int do_plain_btf".
> > >
> > > Fixes: 99f9863a0c45 ("bpftool: Match maps by name")
> > > Cc: Paul Chaignon <paul.chaignon@orange.com>
> > > Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> > > ---
> >
> > just one nit below
> >
> > Acked-by: Andrii Nakryiko <andriin@fb.com>
> >
> > >  tools/bpf/bpftool/map.c | 42 ++++++++++++++++++++---------------------
> > >  1 file changed, 20 insertions(+), 22 deletions(-)
> > >
> > > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> > > index e00e9e19d6b7..45c1eda6512c 100644
> > > --- a/tools/bpf/bpftool/map.c
> > > +++ b/tools/bpf/bpftool/map.c
> > > @@ -933,7 +933,7 @@ static int maps_have_btf(int *fds, int nb_fds)
> > >
> > >  static int
> > >  map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
> > > -        bool enable_btf, bool show_header)
> > > +        bool show_header)
> > >  {
> > >         void *key, *value, *prev_key;
> > >         unsigned int num_elems = 0;
> > > @@ -950,18 +950,16 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
> > >
> > >         prev_key = NULL;
> > >
> > > -       if (enable_btf) {
> > > -               err = btf__get_from_id(info->btf_id, &btf);
> > > -               if (err || !btf) {
> > > -                       /* enable_btf is true only if we've already checked
> > > -                        * that all maps have BTF information.
> > > -                        */
> > > -                       p_err("failed to get btf");
> > > -                       goto exit_free;
> > > +       if (wtr) {
> > > +               if (info->btf_id) {
> >
> > combine into if (wtr && info->btf_id) and reduce nestedness?
> There is other logic under the same "if (wtr)".
> Thus, it is better to leave it as is.

My bad, missed those tiny minuses in diff :) Of course that would be incorrect.

> and this indentation will be gone in patch 5.
>
> >
> >
> > > +                       err = btf__get_from_id(info->btf_id, &btf);
> > > +                       if (err || !btf) {
> > > +                               err = err ? : -ESRCH;
> > > +                               p_err("failed to get btf");
> > > +                               goto exit_free;
> > > +                       }
> >
> > [...]

Patch
diff mbox series

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index e00e9e19d6b7..45c1eda6512c 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -933,7 +933,7 @@  static int maps_have_btf(int *fds, int nb_fds)
 
 static int
 map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
-	 bool enable_btf, bool show_header)
+	 bool show_header)
 {
 	void *key, *value, *prev_key;
 	unsigned int num_elems = 0;
@@ -950,18 +950,16 @@  map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
 
 	prev_key = NULL;
 
-	if (enable_btf) {
-		err = btf__get_from_id(info->btf_id, &btf);
-		if (err || !btf) {
-			/* enable_btf is true only if we've already checked
-			 * that all maps have BTF information.
-			 */
-			p_err("failed to get btf");
-			goto exit_free;
+	if (wtr) {
+		if (info->btf_id) {
+			err = btf__get_from_id(info->btf_id, &btf);
+			if (err || !btf) {
+				err = err ? : -ESRCH;
+				p_err("failed to get btf");
+				goto exit_free;
+			}
 		}
-	}
 
-	if (wtr) {
 		if (show_header) {
 			jsonw_start_object(wtr);	/* map object */
 			show_map_header_json(info, wtr);
@@ -1009,7 +1007,7 @@  static int do_dump(int argc, char **argv)
 {
 	json_writer_t *wtr = NULL, *btf_wtr = NULL;
 	struct bpf_map_info info = {};
-	int nb_fds, i = 0, btf = 0;
+	int nb_fds, i = 0;
 	__u32 len = sizeof(info);
 	int *fds = NULL;
 	int err = -1;
@@ -1029,17 +1027,17 @@  static int do_dump(int argc, char **argv)
 	if (json_output) {
 		wtr = json_wtr;
 	} else {
-		btf = maps_have_btf(fds, nb_fds);
-		if (btf < 0)
+		int do_plain_btf;
+
+		do_plain_btf = maps_have_btf(fds, nb_fds);
+		if (do_plain_btf < 0)
 			goto exit_close;
-		if (btf) {
+
+		if (do_plain_btf) {
 			btf_wtr = get_btf_writer();
-			if (btf_wtr) {
-				wtr = btf_wtr;
-			} else {
+			wtr = btf_wtr;
+			if (!btf_wtr)
 				p_info("failed to create json writer for btf. falling back to plain output");
-				btf = 0;
-			}
 		}
 	}
 
@@ -1050,7 +1048,7 @@  static int do_dump(int argc, char **argv)
 			p_err("can't get map info: %s", strerror(errno));
 			break;
 		}
-		err = map_dump(fds[i], &info, wtr, btf, nb_fds > 1);
+		err = map_dump(fds[i], &info, wtr, nb_fds > 1);
 		if (!wtr && i != nb_fds - 1)
 			printf("\n");
 
@@ -1061,7 +1059,7 @@  static int do_dump(int argc, char **argv)
 	if (wtr && nb_fds > 1)
 		jsonw_end_array(wtr);	/* root array */
 
-	if (btf)
+	if (btf_wtr)
 		jsonw_destroy(&btf_wtr);
 exit_close:
 	for (; i < nb_fds; i++)